1. Field of the Invention
This invention relates to a novel method and system for transporting, assembling, storing, and disassembling oilfield tubulars in and around a single drilling deck, derrick, and rotary system while drilling operations are simultaneously and independently occurring.
2. Description of the Related Art
Drilling for oil and gas with a rotary drilling rig is being undertaken to increasingly greater depths both offshore and on land. The increase in depth translates into longer drilling time, and increased cost. The cost to operate such rigs is already substantial (rental rates for some offshore rigs can exceed U.S. $400,000 to $500,000 per day). Therefore, any productive operation that can be accomplished independently of drilling operations to save even small amounts of time in the drilling process is economically significant.
The term “tubular” as used herein means all forms of drill pipe (including heavy weight drill pipe, such as HEVI-WATE™ tubulars), casing, drill collars, liner, bottom hole assemblies, and other types of tubulars known in the art. HEVI-WATE™ is a registered trade mark of Smith International, Inc. of Houston, Tex. Drilling operations require frequent stops when a small part of the tubular string extends above the drilling deck. Additional tubulars must be moved from a storage rack and connected with the upper end of the tubular string, which may cause significant delay in drilling. The length of a typical single drill pipe section is 30 feet (about 10 m). A stand is created by connecting together two or more single sections of tubulars. In the past, stands have been assembled or made up with four or five single sections of tubulars. A top drive rotary system is often used in place of the rotary table to turn the drill string, and is now the prevalent method of rotary drilling. One of the benefits of the top drive is that it can drill with pre-assembled tubular stands. Therefore, the creation and handling of tubular stands independently of the drilling process is a potentially important way to save time and money.
A method and system of handling tubulars simultaneously with drilling operations is described in U.S. Pat. No. 4,850,439 to Lund, the disclosure of which is incorporated herein by reference for all purposes. Lund proposes a preparation hole and an auxiliary hoist for offline stand building. While drilling operations are occurring, Lund proposes a first tubular being lifted in a vertical position when the auxiliary hoist is moved upward so that the tubular is swung from the cable over and then lowered into the preparation hole. Lund proposes that another tubular can then be swung over the first tubular for connection ('439 patent, col. 7, ln. 58 to col. 8, ln. 19). For a third tubular, if the free space below the top of the preparation hole is less than the length of two tubulars, Lund proposes another auxiliary hoist. In such circumstance, the preparation hole must be displaced or tilted from the vertical suspension line of the first auxiliary hoist ('439 patent, col. 9, ln. 58 to col. 10, ln. 46).
Another offline stand building method and system has been proposed by Smedvig Asia Ltd. of Singapore. Smedvig proposes a self erecting offshore tender rig to transfer and erect drilling equipment on a platform. After the drilling equipment is erected on the platform, Smedvig proposes a high line cable system to move tubulars from the tender rig to the platform, a racker crane at the top of the derrick that moves parallel to the drilling deck, and two preparation holes.
Smedvig proposes that while drilling operations are occurring on the platform, a single tubular on the rig can be manually connected at both ends while in horizontal position to the high line cable system. The high line cable system is used to lift and transport the tubular across the water from the rig to the pipe ramp on the platform, where the tubular is manually disconnected. A gripping device connected by cable to a hoist on the racker crane is then manually connected to the upper end of the tubular on the pipe ramp. The tubular is then hoisted in the vertical position, and swung from the cable over the first preparation hole. The tubular is then lowered into the hole, and the gripping device released. The process can be repeated with a second tubular, which can be swung into position in the second preparation hole. The process can be repeated with a third tubular for connection with the first tubular into a double stand. The double stand is then hoisted by the racker crane and lowered for connection with the second tubular for a triple. The completed stand is hoisted up and carried by the racker crane to a vertical tubular storage rack at the top of the derrick. Smedvig also proposes that the first preparation hole can have an adjustable bottom for acceptance of different size tubulars.
Another offline stand building method and system is proposed in U.S. Pat. No. 6,976,540 to Berry, the disclosure of which is incorporated herein by reference for all purposes. Berry proposes, among other things, a load and preparation pipe handling device (“preparation device”), a storage pipe handling device (“storage device”), and tubular storage areas at the top of the derrick. The preparation device includes a vertical truss rotatable about its longitudinal axis. The preparation device includes a gripping device attached at the end of a hoisting cable extending out from the vertical truss. The gripping device is manually attached to one end of a tubular that has been placed near the preparation device on the catwalk or the pipe ramp so that when the cable is retracted back toward the preparation device, the lifted tubular is swung from the cable, similar to the Lund and Smedvig systems.
Berry then proposes that the truss can then swing the vertical tubular in a circular path to a first preparation hole, which has been placed along the path. The preparation device can then lower the first tubular into the first preparation hole. Using two preparation holes, much like the Smedvig system, a stand is assembled. The assembled stand is then lifted vertically by the preparation device to the top of the derrick, and directly exchanged to the storage device, which can either store it or transport it for drilling operations ('540 patent, col. 7, lns. 26-40 and col. 8, lns. 30-35).
The oil industry has proposed systems for the online transferring of tubulars from the horizontal position on a pipe rack to the vertical position over the well center. One such system is proposed in U.S. Pat. No. 4,834,604 to Brittian et al., the disclosure of which is incorporated herein by reference for all purposes. Brittian proposes a strongback connected to a boom that is pivotally fixed to a base located adjacent to the rig. The strongback transfers the tubular directly through the V-door from a horizontal position to a vertical position so that a connection between the tubular and the tubular string can be made. Another system is proposed in U.S. Pat. No. 6,220,807 to Sorokan, the disclosure of which is incorporated herein by reference for all purposes. An online pipe handling system is proposed for using a bicep arm assembly pivotally connected to a drilling rig, and a forearm assembly and a gripper head assembly both pivotally connected to the bicep arm assembly. The gripper head assembly grabs the horizontal positioned tubular on the pipe rack adjacent to the rig, and rotates the tubular to a vertical position over the well center.
A horizontal to vertical pipe handling system is proposed in Pub. No. US 2006/0151215 to Skogerbo. Skogerbo discloses an Eagle Light/HTV-Arm, which is distributed by Aker Kvaerner MH of Houston, Tex. The Eagle Light HTV (horizontal to vertical) device is proposed for online transfer of tubulars from a horizontal position at the catwalk to a vertical position in the derrick directly over the well center or into the mousehole. Aker Kvaerner MH also distributes bridge crane systems and storage fingerboards. National Oilwell Varco of Houston, Tex. also manufactures a similar HTV online pipe handling device.
Another online method and apparatus for transferring tubulars between the horizontal position on the pipe rack to the vertical position over the well center is proposed in U.S. Pat. No. 6,705,414 to Simpson et al. Simpson proposes a bucking machine to build tubular stands in the horizontal position on the catwalk. A completed stand is horizontal at a trolley pick-up location, and becomes vertical at the rig floor entry. The stand, clamped to a trolley, is pulled along and up a track with a cable winch. A vertical pipe racking device located in the upper derrick is proposed to transfer the stand directly from the trolley.
The disadvantages of the above tubular handling methods and systems include significant human physical contact with the tubulars and lifting equipment at numerous times and locations, which can result in costly delay or possible injury. The alignment and transfer operations are lengthy and complex. The paths of the tubulars in the offline stand building are not fully restricted, which creates delay and safety hazards. The offline stand building operation may be interrupted when equipment is being used in the online drilling operations. Therefore, a more efficient method and system for handling tubulars that minimizes or eliminates human physical contact with the tubulars and lifting equipment, restricts and controls the path of the tubulars throughout the entire offline operation, requires minimal inefficient movement of the tubulars, and eliminates any potential interruption of the tubular building and drilling process would be desirable.